As is well known, in making graphic art mockups, layouts and the like, it is necessary to affix photographs, writing material, pictures, or other reproduction proofs, etc., to a background sheet of material, such as for example paper or cardboard backing. Often times, in making such mockups and layouts, it is necessary to reposition the photographs or other reproduction proofs after they have been affixed to the background sheet. Thus, it is desirable that the photographs and other reproduction proofs be coated with a pressure sensitive or other releasable types of adhesive which permits the photographs, materials, pictures, etc. to be affixed and repositioned many times in order to obtain a desired pattern or layout.
Generally in the prior art, the pressure sensitive or other adhesives utilized comprise some form of wax material. In order to apply such wax material to the sheet items, various types of wax coaters are known. Such applicators generally include suitable heater devices of some kind to keep the wax in a molten or fluid state. Further, the reservoir for the molten wax material is generally open to the surrounding atmosphere such that the wax material will tend to evaporate and/or dry out during nonuse.
While other types of adhesive or glue materials are known which do not require heating, such adhesive materials usually employ a solvent to keep the adhesive in a fluid state and which must also be capable of evaporating rapidly in order to bond the adhesive coating to the sheet items. This thus creates a problem in connection with open container systems, since the solvent materials tend to continually and prematurely evaporate while in the adhesive mixture.
U.S. Pat. No. 3,608,515 is directed to an applicator apparatus in which an adhesive mixture containing a solvent is held in a reservoir and is kept from evaporating from the reservoir by employing a relatively large housing which substantially completely encloses the reservoir, applicator member, and related components from the atmosphere which surrounds the housing. The housing includes a sealing cover which is adapted to be moved away from the path along which a sheet or webbing material passes when it is desired to apply an adhesive to the sheet material. In this manner, the applicator member is exposed to apply a coating to the sheet or webbing material. When the apparatus is not in use, the sealing cover is positioned to seal the interior of the housing from the surrounding atmosphere to prevent evaporation and drying out of the adhesive material and/or solvent within the reservoir.
The present invention is directed to an improved apparatus for applying coating materials to sheet materials which is particularly useful in connection with providing a substantially compact, closed system of a simplified construction for the coating material and related components in contact therewith when the apparatus is not being used, and thus is generally directed to improvements over the arrangement shown and described in U.S. Pat. No. 3,608,515. In particular, the present invention is directed to improvements with respect to means for separating the sheet materials from the applicator roll as the sheet material is moved therepast, as well as improvements in connection with sealing of the coating materials and components in contact therewith when the apparatus is not in use so as to provide a very compact and yet sealed system. Further, improvements in connection with providing adjustment of the coating thickness to be applied to the sheet materials are also disclosed.